There is a need to know the loads imparted into an aircraft landing gear during an abnormal loading event (such as a hard landing or off-runway excursion), in order to determine whether the landing gear is still usable after such an event. If the vertical and drag loads in the axles of the landing gear can be known, these can be combined with side load and shock absorber closure to determine the loads in each major landing gear component.
Current installations are based on traditional sensors (e.g. strain gauges), and are limited to flight test use or have performance limitations. Robust installations are difficult to achieve inside an axle due to the mounting requirements (e.g. accuracy of positioning, orientation, temperature, surface finish). Also, the life of such sensors can be limited, and replacement very difficult. Other than what is used for flight test aircraft, no in-service system for detecting an overload is currently known.